Method and apparatus for duplicating text, pictures and the like on unprepared copy receiving sheets



DEG 3, 1968 s. B. KVARNEGARD M HOD AND APPARATUS FOR DUPLICATING THELIKE ON UNPREPARED COPY RECEIVING SHEE Filed nec. 1, 1965 De 3, 1968 s.B. KVARNEGARD 3,414,724

METHOD AND APPARATUS FOR DUPLICATING TEXT. PICTURES AND THE LIKE ONUNPREPARED COPY RECEIVING SHEETS Filed DSC. l. 1965 2 Sheets-Sheet 2United States Patent O 3,414,724 METHOD AND APPARATUS FOR DUPLICATINGTEXT, PICTURES AND THE LIKE ON UNPRE- PARED COPY RECEIVING SHEETS SvenBertil Kvarnegard, Enebyberg, Sweden, assigner to Aktiebolaget CarlLamm, Maskinatfar, Stockholm, Sweden, a joint-stock company of SwedenFiled Dec. 1, 1965, Ser. No. 510,833 Claims priority, applicationSweden, Dec. 11, 1964, 15,055/ 64 6 Claims. (Cl. Z50-65) ABSTRACT F THEDISCLOSURE A thermographic copying method and apparatus for repeatedpositive reproduction of an original onto copy sheets, which comprises-a rotary glass drum having an internal source of infrared radiation,the original to be copied being mounted with the heat-responsive indiciathereon in contact with the external surface of the drum and a beltcarrying a coating of a heat-fusible dye composition is arranged to bepressed by a roller against the back of the original to cause the dye tobe picked up by it at those heated places in register with the indiciato be copied; then a second roller presses a copy sheet of paper againstthe outside of the original to pick up an imprint of the dye imagetherefrom whereupon the copy sheet is separated from the original. Thelatter is then re-coated with dye and the cycle repeated.

This invention relates to a method and an apparatus for Aduplicating onunprepared copy receiving sheet materials such text, pictures and likeindicia which have [been previously made by typewriting, printing or byhand on an original record or so-called master sheet in opaque ink or asimilar application medium that is capable of absorbing infrared lightradiation while thereby increasing its temperature and presupposes theutilization of concentrated light radiation of high intensityparticularly within the range of infrared radiation for transferring afusible copy printing dye composition having a negligible absorptioncapacity of its own as regards the utilized radiation from a carrier ofa thin coating of said dye composition to the copy receiving sheet inaccordance with the text and other indicia appearing on the originalrecord.

The invention is based on the well-known fact that, if an originalrecord which has been made in the abovementioned way on a base sheet,preferably of paper, having in itself a comparatively low absorptioncapacity as regards the said radiation, is exposed to radiation of thekind mentioned during a limited time interval, the text and otherindicia applied to it will assume an appreciably 'higher temperaturethan the blank areas. The difference in temperature thus obtainedbetween different areas olf the original can be utilized for copyingpurposes by employing a substantially wax-like copy printing dyecomposition, which is heat-sensitive and fusible in such a way that itmelts or softens to the point at which it becomes transferable Within atemperature interval that lies mainly between the temperature obtainedin the blank areas of the original record as a result of its exposure tothe radiation and the temperature obtained in the indicia bearing areasof the ori-giice nal record under the same circumstances, and by lettingthis dye composition become subjected to the action of the differentlyheated areas of the original record under such conditions that dye istransferred only within those areas which correspond to the indicia onthe original record.

As already pointed out, the temperature-sensitive copy printing dyecomposition should have a negligible absorption capacity of its own inregard to the infrared radiation, so that at all events the thincoatings or layers olf dye composition which are required for thecopying process cannot themselves absorb such an amount of the raditionthat they become heated into a transferable or molten condition withoutthe aid of the -additional heat received from the indicia bearing areasof the original recor-d. However, such dye compositions of various kindsan-d colours are Well known in the prior art, and it is also assumed tobe known, that a copy produced by means of such a dye compositioncannot, as a rule, be used itself as an original or master for renewedduplication according to the same method, because it is for obviousreasons hardly possible to obtain the required temperature differencebetween the blank and indicia bearing areas of such a copy by subjectingit to radiation.

Although the basic principles of the copying method mentioned above,hereinafter simply called the thermographic fusible dye process, havebeen known for a long time, the method has still its perceptible limits,at least in the forms it has hitherto been more commonly practised.Despite the geniality of the basic idea and the considerable advantagesof the process in question over other copying methods it has so far notbeen possible Ifor practical reasons to use the thermographic fusibledye process for quick duplication of a plurality of copies from a singleoriginal record. This invention offers a solution of this particularproblem and makes it possible to apply the thermographic fusible dyeprocess in the speedy production of practically unlimited series ofcopies from an original record in about the same manner as has hithertoonly been possible by making use of the well-known spirit or stencilduplicating processes.

Compared to the latter processes, which have hitherto been practicallythe only ones used in the office branch, the thermographic fusible dyeprocess according to this invention offers great and obvious advantages,above all because it makes it unnecessary to use so-called master sheetswith easily spoiled and quickly consumed dye layers, transfer orhectographic carbon sheets with easily-soluble, finger-soiling dyecoatings and bad-smelling or otherwise disagreeable liquids, or smearycolours and stencil sheets which are very ditiicult to store betweenuses respectively. Furthermore, the thermographic fusible dye processoffers valuable advantages when it comes to copying of only selectedportions of the original record, which advantages are very expedient inconnection with so-called selected line-transfer works and similar caseswhen it is desirable to make a copy only of certain selected parts ofthe text etc. on the original record.

If the thermographic fusible dye process shall at all be able to offer apractically valuable and thus competitive alternative to spirit orstencil duplicating processes, it must, however, be carried out in sucha manner that the copy printing dye composition is transferred to thefront surface of the copy receiving sheet, so that the use ofparticularly thin and transparent copy sheets is not necessary and sothat different reproductions can be made on the respective sides of agiven copy sheet when so desired. This requirement is well satisfied inaccordance with the invention which as far as the character of the copysheet is concerned does merely require that the surface of the copysheet shall lbe able to give hold for the dye composition when thelatter tends to adhere to it. On the other hand, the invention requiresthat the original record shall be made on a sheet material which only toa negligible degree impedes the passage of the radiation used, in whichcase the text indicia are applied in mirror image on the back of therecord, or preferably, on a sheet mate` rial which is so thin orotherwise so constituted that it permits a heat transmission-either byconduction or by so-called dark radiation-from the heat-absorbinginkcoated portions on the one side thereof to its other side surfacewithout appreciable dispersion in the plane of the sheet, which couldmake the copy obscure, in which case the text indicia can be applied inordinary, true fashion on the front side of the original record.

The mirror image text just mentioned can, of course, be easily producedby placing an ordinary carbon paper in reversed position on the rearside of the original when the latter is typed in a typewriter orprepared by handwriting, provided that the carbon paper is coated withan opaque, radiation-absorbing ink. In many cases a combination of atrue image writing on the front face of the original record and a mirrorimage writing prepared as just explained on the back thereof may befound particularly advantageous to obtain more distinct copies.

The method according to the invention is now mainly characterized inthat the original record while performing an uninterrupted cyclicalmovement is first passed through a zone i-n which the one side of theoriginal record is exposed to said concentrated light radiation, whileat substantially the same time the other side thereof is brought intointimate contact with the dye-coated surface of said carrier, which ismoved synchronously with and in the same direction as the passingoriginal record so that a first transfer of dye composition from saidcarrier to those areas on said other side of the original record whichcorrespond to the text and other indicia is effected, then separatedfrom said dye-coated carrier and pressed with the side now partlycovered with dye composition against said copy receiving sheet for asecond transfer, in which the dye composition spots, on the originalrecord previously received from the carrier are brought to adhere, atleast to a substantial extent, to the copy receiving sheet, and finallyseparated from the copy receiving sheet, now bearing the finished copy,to be immediately ready for repeating its operating cycle.

The double transfer of the dye composition first from the carrier to theoriginal record and subsequently therefrom to the copy receiving sheetmay seem complicated at the rst glance but is very easy to accomplish inpractice, as will appear from the following, and the method has provedto give a surprisingly good copy clearness while at the same timeoffering possibilities for very advantageous apparatus constructions.

Although not always necessary, the original record can to advantage beexposed to a second irradiation of infrared light while being pressedagainst the copy receiving sheet, whereby the dye composition may moreeasily be given away from the same. This second irradiation may in manycases be less intensive than the first one and independent thereof andis preferably produced by a second source 0f radiation which is separatefrom the first source but also irradiates through the envelope wall ofthe drum. When such double radiation is utilized, it may also be foundadvantageous to cool the original record between the two irradiations inorder to govern any tendency of the dye composition to ow out, withobscure copies as a result. Howe-ver, in most cases such cooling isunnecessary.

In principle the carrier of the thin coating of copy printing dyecomposition may, of course, be any suitable surface which has beencoated with the dye composition in question and which can be broughtinto close contact with the rear side of the original record during thefirst irradiation. It has, however, been found most suitable to use acarrier in the form of an endless web which can be passed, as its dyecomposition coating is successively consumed during the copying process,through a dye applicating, coating renewing device or mechanism beforeit is again brought into contact with the original record. Alternativelythere may be used a long and easily exchangeable precoated web runninglbetween two spools.

As already mentioned the invention is also concerned with a duplicatorapparatus operating in accordance with the directions given hereinbeforeand this apparatus is of the kind comprising a rotary drum, the envelopewall of which at least partially consists of a material, preferablyglass, having a high permeability to infrared light radiation, aradiation source unit mounted inside said envelope wall of the drum andhaving a high intensity particularly within the infrared radiationrange, said unit being adapted to deliver a concentrated radiationthrough the radiation-permeable envelope wall portion of the drum to atleast one radiation zone that extends axially relative to the drum, anda feeding mechanism for the copy receiving sheets including among otherdetails a pressure roller adapted to be resiliently pressed towards thedrum, and is mainly characterized in that said drum is adapted todetachably hold on its outside an original record so that the latterwill at least partly extend over the radiation-permeable portion of theenvelope wall of the drum and partake in the rotation thereof, that amovable carrier having a surface coated with a thin layer of a fusiblecopy printing dye composition is arranged first to go into intimatecontact with the outside of said original record on said drum withinsaid zone which said radiation source unit irradiates through theradiation-permeable envelope wall portion of the drum, and then todepart from said drum, that said pressure roller serving to press thecopy receiving sheets against the original record held around the drumis mounted behind the point, as viewed in the direction of rotation, inwhich said dye-coated carrier departs from the drum, and that saidfeeding mechanism includes, in adidtion to said pressure roller, membersserving to part the finished copy from the original record at a pointbehind the pressure roller.

With an apparatus of the type thus defined it is possible to producelarge series of copies of one and the same original record in rapidsuccession Without in any way subjecting said original record to Wear ordamage so that it becomes difiicult to store or inapt for completionwith additional text if so should be desirable.

For a further elucidation of the invention reference is made in thefollowing to the accompanying drawings, in which FIG. 1 illustrates in agreatly enlarged and rather diagrammatical form the duplicating methodaccording to the invention and at the same time the basic mode ofoperation of the duplicating apparatus forming part of the invention,while FIG. 2 shows, on a reduced scale, a longitudinal section through acomplete duplicating apparatus embodying the invention in which,however, some detail arrangements have been given a very simplified anddiagrammatical form for the matter of simplicity, since it is believedthat a man skilled in the art will be fully capable to understand how toconstruct those details himself after having read the followingdescription and directions.

For illustrating the duplicating method according to the inventionreference is primarily made to FIG. 1, in which numeral 1 designates apart o-f the envelope wall of a rotary drum, which envelope wall is madeof glass or some other material that is highly permeable to the infraredradiation used in the duplicating process. The drum 1 encloses aradiation source unit, generally designated by 2, which in any suitablemanner is stationary but possibly adjustably mounted, so that theenvelopel wall of the drum 1 moves past it when revolving in thedirection indicated by the arrow A Preferably, but not necessarily, theradiation source unit consists of two separate and elongate radiationsources 3, and 4 respectively, of the tubular infrared-radiator type, inwhich a normally coiled resistance wire is mainly centrally supported ina cylindrical quartz tube, and each radiation source is provided with asubstantially elliptical reflector 5, and 6 respectively, capable ofconcentrating the radiation so that it passes through the envelope wallof the drum 1 and forms two radiation zones 7, and 8 respectively, of avery constricted width and which are peripherally separated and extendaxially relative to the drum. Instead of using two radiation sources, itmay in some cases be sufficient to use a single one, which should thenbe arranged similarly to the radiation source 3 to provide the radiationzone 7, which is the most important one. It is also possible todistribute the radiation from a single radiation source to both the tworadiation zones 7 and 8 by means of a reflector arrangement, althoughthis will ordinarily bring about rather considerable radiation lossesand accordingly an unnecessarily high heating of the space within thedrum as well as problems with the adjustment of the radiant power in thetwo radiation zones.

Retained in some suitable manner on the outside of the envelope wall ofthe drum 1 is an original record 9 which is, in the example shown inFIG. 1, provided with text indicia on its front side, i.e. the sidefacing the drum 1, whereby this text can be made true in the normalmanner, provided that the original record 9 is made on a base sheet,e.g. of paper, which allows heat transmission through it without toomuch dispersion. The text indicia 10 are made by the application of anopaque, radiation-absorbing ink or the like, and the base of theoriginal must be of such a nature that its textfree, blank areas willonly absorb a very inferior quantity of the infrared radiation. Asalready mentioned in the introduction the original record 9 may,however, alternatively be made on a base sheet which in itself does onlyinsigniiicantly or not at all inhibit the passage of the infraredradiation from the radiation source unit 2, in which case the textindicia can be applied by means of an opaque, radiation-absorbing ink orpigment in reversed or mirror writing on the rear side of the record,i.e. the side thereof which is turned away from the drum, or even onboth sides of the base sheet. Thus, the essential thing is that, duringthe irradiation from the radiation source unit 2, the surfacetemperature of those portions or spots on the rear or outer surface ofthe original record 9, which correspond to the text indicia, shallbecome distinctly increased relative to the surface temperature of allthe other areas of the same rear surface of the record which correspondto blank or indicia-lacking portions of the record.

Disposed substantially right in front of the first radiation zone 7through which the original record 9 attached to the outside of drum 1 ispassing during the rotation of the drum in the direction indicated byarrow A and pressed against the outwardly facing rear side of record 9and radially towards the drum l-at least during the copying process-is acomparatively soft, e.g. spongerubber-coate-d, roller 11 over whichpasses a conveyorlike carrier web 12, which can to advantage be made ofpaper with great tensile strength, plastic sheeting (preferably nylon)or any other suitable iiexible material, and which carries on its outersurface, when arriving to the roller 11, a thin and uniform coating 13of the previously specified copy printing dye composition which istransferable after having been heated into a softened or molten state.By means of the conducting roller 11 fresh parts of the dye-coated web12 are perpetually pressed against the rear side of the passing originalrecord 9, and due to the nature of the dye composition at least parts ofthis composition coating will then be transferred from the web 12 tothose portions or spots on the rear side of the record 9 whichcorresponds to the text. indicia appearing on that record. Consequentlythe original record itself will, when being subsequently separated fromthe web 12 as a result of the web deliecting function of the roller 11,take over and with it certain limited portions or spots 14 of the dyecomposition coating 13 of the web 12, so that the said coating on theweb 12 is partly consumed as shown diagrammatically in FIG. l. It willbe obvious that this partial transfer of the portions 14 of the dyecomposition coating 13 requires that the surface of the original recordsheet must be of such a nature that the dye composition in its heated ormolten state will readily adhere to it. With this transfer the firststage `of the duplicating process according to the invention isfinished, and the original record has thereby in itself become a sort ofmaster prepared for the duplicating 'task proper and to a certain extentresembling an inked lithographie printing plate, although produced in adifferent way.

It has `been observed in some cases that the portions or spots 14 of thedye composition transferred from the layer 13 to the rear or outersurface of the original 9, may show a tendency to iiow out and so renderthe contours of the indicia images obscure. The cause of this may beeither that the surface of the original record sheet is not quite ideal(possibly too porous so that a sort of blotting-paper-effect results),that the melting heat requirement of the dye composition is much toolow, or that the heat quantity produced by the radiation is not verywell balanced to the actual working conditions of the apparatus, i.e.the nature of the original, the properties of the available dyecomposition, and the radiation intensity. Such flowing out tendenciescan, however, be governed in a very simple way by providing theapparatus with a tubular nozzle 15 mounted for instance at a guide plate16 as shown in the drawing and supplying cooling air to the rear side ofthe original record 9 from a suitable little pump or compressor (notshown in the drawing) within the area immediately behind the roller 11.However, if the apparatus is intended for work with only one single,predetermined type of original records and with a dye composition havingpermanently the same properties, such cooling may of course be dispensedwith and the radiation intensity in the zone 7 instead be exactlyadjusted once for all. The cooling nozzle 15 can also be omitted whensome obscurity of the copy can be accepted, for instance to cut themanufacturing costs for the apparatus.

As a result of the rotation of the drum 1 the prepared original recordis in the example shown in the drawing very soon brought to pass throughthe second radiation zone 8, in which the infrared radiation need notnecessarily be as intensive as in the radiation zone 7. In the radiationzone 8 a second absorption of radiation will take place within the textindicia bearing areas 10 of the record 9 and thus also an indirectheating of the portions or spots 14 of fusible dye composition adheringto the outer rear side of the record. The very moment these dyecomposition portions or spots reach the temperature needed to becomefused or at least sticky, the rear side of the original record '9 isbrought into contact with a copy receiving sheet 17, e.g. a sheet ofordinary paper, cardboard or the like, which the guide plate 16 steersin between the drum 1 and a pressure roller 18. The said roller 18 ispressed radially against the drum during the duplication and has acomparatively hard surface of rubber or a similar material with a highfriction coefficient. In certain cases a slight preheating of the copyreceiving sheet 177 before it is brought into contact with the originalrecord 9, may be found advantageous, but normally such special steps arenot required. The copy receiving sheet does not need to be of anyparticular quality nor does it need any preparation `for instance withchemicals, but it should obviously afford a good base of adhesion forthe dye composition. Of course, the copy receiving sheet 17 does n-otneed to be transparent nor to have any specific properties with respectto the infrared radiation used in the copying process. The dyecomposition portions or spots 14 previously transferred to the rear sideof the original record 9 and softened through heating in the secondradiation zone 8 will, of course, readily adhere to the copy receivingsheet 17 when the latter is pressed against the record at a pointlocated substantially right in front of or, as has been shown, slightlyafter the radiation zone 8. As pointed out already, the radiation zone 8may be omitted but, if so, the distance between the radiation zone 7 andthe pressure roller 18 should be chosen as short as possible, or thedrum 1 should rotate at quite a high speed. Furthermore the coolingnozzle 1S should in such a case be dispensed with.

Already immediately behind the pressure roller 18, but preferably alittle farther away from it, as shown, the copy sheet 17 is in its turnseparated from the original record 9 as indicated by the arrow B. Theportions or spots 14- of the dye composition will at this time be atleast partially transferred to the copy sheet and form on the latter atrue copy of the text and other indicia on the original record. It istrue that certain residues of the dye composition will normally be lefton the rear side of the original record but these residues have provedcompletely harmless for the utilization of the same record 9 in therepeated duplicating process and also for the filing and handling of theoriginal record after duplication, since the dye composition will notgive off any dye and is not sticky at normal room temperature or, as arule, at temperatures below approximately to 40 C.

How far the copy receiving sheet 17 should follow the original record 9before being separated therefrom depends very -much on the nature of thedye composition and must thus be determined empirically in eachparticular case. Commonly it seems to be so, however, that a very earlyseparation of the copy from the original record results in transfer ofonly a smaller part or thickness of the dye composition than a morepostponed separation. The reason for this may be that the dyecomposition congeals so to say layer by layer in the direction from thecomparatively cold copy sheet 17 toward the comparatively warm originalrecord 9.

FIG. 2 shows more in detail how a complete duplicator apparatusembodying the invention can be constructed. The drum 1 is rotatablymounted between two longitudinally extending side walls on theapparatus, one of which is visible at 20. Mounted between the side wallsare also two feeding rollers 21 and 22 one of which, 22, is driven andcircumferentially covered with sponge rubber. The feeding rollers 21 and22 serve to feed the copy receiving sheets 17 to the pressure roller 18past the guide plate 16 previously referred to as wcll as further guideplates 23, 24 and 25 respectively, from a feed table 26 at the front endof the machine, on which the fresh copy receiving sheets are suitablystored in a pile. Any suitable known devices may, of course, be used toautomatically feed the copy receiving sheets 17 one by one onto thefeeding rollers 21 and 22. The pressure roller 18 is mounted between twobell-crank levers 27, the downwardly extending arms of which areactuated by tension springs 28, the tension of which can -be varied byturning an eccentrically mounted rod 29 in order to adjust the pressureexerted by the pressure roller 18 against the drum 1.

The conducting roller 11 of the belt-like carrier web 12 is in its turnmounted between side walls 30 belonging to an insert, which is removablysuspended in the front part of the duplicator apparatus and is shaped soas t0 urge the roller 11 towards the drum 1 by its own weight. In fact,this insert forms a complete dye applicating unit comprising a trough 31containing the dye composition 32, and an electrically heated transferroller 33 dipping its underside into the trough so that it can, duringits rotation, apply fresh dye composition to the passing web 12 andsmooth out the remaining coating of dye composition thereon so as tocompletely restore said coating. A likewise electrically heated scraperdevice 34 serves to scrape off superfluous dye composition from the web12 and so bring the coating 13 (FIG. l) on the latter to the appropriatethickness-ordinarily not exceeding some hundredths of a millimeter. Thescraper device 34 also dips its lower portion into the trough 31 and isshaped as a pocket 35, in which sticks or like pieces of fresh dyecomposition can be received and melted to thereafter enter the trough 31in a uid state. Having passed the scraper device 34 the web 12 is bentover a cooling roller 36 which is mounted between two pivoted arms 37,which are loaded by springs 38 in order to keep the endless web 12 wellstretched. Preferably, the cooling roller 36 is cooled by an air streamfrom a fan (not shown). After having passed the cooling roller 36 theweb 12 is ready to return to the conducting roller 11.

Behind the drum 1 there is provided a belt or rubber string conveyorwhich serves to separate the finished copies from the original record 9on the drum and transport them to a discharge table 40 provided at thetop 0f the rear part of the duplicator apparatus, so that the operatorcan continuously check the copying result even when standing, as isnormally the case, in front of the apparatus, i.e., to the left in FIG.2. The said conveyor comprises several endless rubber belts or strings41 running parallelly to each other between lower and upper pulleys 42,and 43 respectively, and the endless belts or strings are driven bycontact with a common, transverse driving roller 44. Those parts of thebelts or strings 41 which pass closest to the drum 1 cooperate with onelower and one upper row of pulleys 45, and 46 respectively, which aremounted between a plurality of parallel, interconnected plates 47 whichform another detachable insert in the apparatus, and the lower ends ofwhich are pointed and adapted to aid in separating the front edge of thecopies from the original record on the drum 1. Mounted on freelyswingable arms 48 between the upper ends of the plates 47 arefree-running auxiliary pulleys 49 which serve to direct the copiesdischarged between the belts 41 and the plates 47 so that -they becomeneatly piled on the table 40.

The drum 1, the envelope wall of which consists for the largest part ofa material readily letting through the infrared radiation from theradiation source unit 2 disposed inside the drum, is provided with anaxially extending out or slot in which is provided a filler member 50accommodating two series of movable jaws, by means of which the originalrecord, and a covering sheet for partial covering of said recordrespectively, can be attached to the drum 1. Two guide plates 51 and 52are provided on the front side of the drum to guide the original record,and the covering sheet respectively, towards the said jaws in thelocation where the ller member Sil of drum 1 is normally intended tostop when the apparatus is to be prepared for a new duplicatingprocedure. The drum 1 is, in fact, rotary mounted between two annularend pieces 53 located one at each end of the drum and in their turnrotary mounted between external supporting rollers 54, secured to therespectively side walls 20 of the apparatus, and furthermoreinterconnected by a screen 55 of limited peripheral extension, which isconcentric with the drum 1 and placed on the inside of the latter. Thedrum 1 can be locked to the end pieces 53 by means of a locking deviceindicated at 56 and is driven via the end pieces 53, to which isprimarily transmitted the rotary motion that is to be imparted to thedrum 1 for execution of the duplication.

The screen 55 has for its object to permit switching on of the radiationsource unit 2 slightly prior to the moment when the original recordattached to the outside of the drum 1 should be irradiated, and this isparticularly valuable when using intermittent operation of the radiationsource unit which has proved most advantageous, because in this way thetotal energy consumption of the apparatus can be reduced to a certaindegree and thus also the problem of removing the superfluous heat thatis inevitably produced within the drum 1 while the radiation source unitis in operation. The screen 35 can also be utilized to screen off aselected part of the original record attached to the outside of thedrum, so that the text on this part will not be reproduced. To this end,the locking device 56 is released and the drum rotated so far relativeto the screen 55 as is necessary to screen off the desired part of theoriginal record.

Inside the screen 55 there is provided, also concentrically with thedrum, an additional diaphragm screen 57 carried between twospring-loaded arms 58, which are centrally pivoted relative to thedrum 1. The diaphragm screen 57 is only swingable to a limited extent inthe downward direction, so that it will temporarily screen off theradiation source unit 2 from the inside of the drum when each singlecopying process is iinished, and particularly so when it is desired toeffect a so-called line transfer, i.e., to prevent duplication of acertain number of text lines on the lower portion of the originalrecord. In the example shown, the diaphragm screen 57 is actuatedthrough friction by a crcumferentially adjustable wart or driver 59provided on the end piece 53, and as soon as this wart has passed theswung-down diaphragm screen, the latter is restored automatically by itssprings. However, at this moment the -radiation source unit 2 hasalready been switched off, and the radiant power possibly remainingafter the switch-olf moment has had no possibility to reach the originalrecord and to thereby cause any undesirable copy producing result. Ofcourse, the diaphragm screen 57 does not need to be used when the entireoriginal record is to be reproduced.

The radiation source unit 2 is carried by a stationary cylinder 60inside the drum 1, and suitable fans (not shown) provide for -an axialiiow of cooling air at least through the annular space lbetween the drum1 and the cylinder 60. The power supply to the radiation lsource unit 2takes place preferably from a built-in transformer 61, while anelectromotor 62 drives the driving roller 44 of the belt conveyor aswell as the feeding roller 22 and the drum 1 via the end pieces 53.Special couplings (not shown) are used to lallow an interruption of thedrum rotation when so desired in order to prepare the apparatus for anew duplicating procedure. When necessary, a driving motion can also beimparted to the web 12 passing through the described dye applicatormechanism in order to prevent it from sliding when in contact with theoriginal record attached to the outside of the drurn 1.

Of course, the duplicator apparatus hereinbefore described can easily beprovided with a plurality of complementary devices, such as means forstepwise rotational adjustment of the drum 1 relative to the end piecesS3 as well as for accurate peripheral adjustment of the wart ordiaphragm screen driver 59 by operation of an easily accessible lever orkey. The web 12 passing through the dye applicator mechanism can, ofcourse, be replaced by a roller of suitable size serving in itself as acarrier of a thin coating of dye composition and being supplied withfresh dye composition during every full revolution in some suitablemanner. In a further thinkable modification the apparatus can be chargedwith a supply roll or spool of web, which has been coated with dyecomposition and can be collected and supplied with fresh dyecornposition in a separate dye application mechanism, or be discarded,after having passed lthe roller 11 or its equivalent replacement. Itshould thus be understood, that the invention is not conned to theembodiment described above and illustrated in FIG. 2, although thisembodiment has proved to work very satisfactorily in prototype tests.

I claim:

1. An apparatus for series-duplicating on unprepared copy receivingsheets of heat radiation absorbent text, pictures and like indiciaappearing on an original While making use of the thermographic fusibledye process and utilizing the original as an intermediate means fortransferring selected spots of dye composition from a carrier of a thincoating of said composition to each copy receiving sheet, said apparatuscomprising in combination:

(A) a rotary drum, the envelop wall of which partially consists of aglass material having a high permeability to infrared light radiation;

(B) means on said drum for detachably mounting the original on theoutside thereof in such a manner that it will be at least partly extendover the radiationpermeable wall portion of the drum and partake in therotation of the drum;

(C) a radiation source unit mounted inside said drum and having a highintensity, panticularly within the infrared radiation range, said unitbeing adapted to deliver a concentrated radiation through saidradiation-permeable wall portion of the drum to form at least oneradiation zone extending axially along the drum;

(D) a movable carrier in the form of a belt-like web having its one sidecoated with a thin layer of the fusible copy printing dye composition;

(E) conducting means for said coated carrier web including a conductingroller arranged to be resiliently pressed towards said drum for bringingthe coated side of the carrier web into intimate contact with theoutside of the original mounted on said drum within said one radiationzone and for subsequently bringing it to depart therefrom;

(F) a feeding mechanism for copy receiving sheets including a pressureroller arranged to be resiliently pressed towards said drum at alocation behind that, where said conducting roller is located, as viewedin the direction of rotation of the drum, said pressure roller beingadapted to press each copy receiving sheet against the original mountedon the drum, and means for separating each such sheet with #the copythereon from the drum-mounted original at a location behind saidpressure roller.

2. An apparatus according to claim 1, wherein said conducting roller forthe coated carrier web has a cornparatively soft, elastically yieldingsurface and said pressure roller for the copy receiving sheets has acomparatively hard, elastic surface.

3. An apparatus according to claim 1, wherein said radiation source unitcomprises two separate, elongated radiation sources provided with each arelated reector, one of said radiation sources being arranged anddirected to form said one radiation zone and the second one beingarranged and directed to form a second radiation zone extending axiallyalong the drum in the neighborhood of the line of contact between saidpressure roller for the copy receiving sheets and said drum.

4. An apparatus according to claim 1, wherein said belt-like web isendless and wherein a dye applicator mechanism passed by said endlessweb is provided to apply fresh dye composition thereto, said applicatormechanism comprising a trough holding the dye composition, heated meansfor distributing the dye composition on said passing web, and means forcooling 'the dye-coated web to a temperature below the softeningtemperature of the composition before the web is again brought intocontact with the original.

5. An apparatus according to claim 1, wherein a radiation-impermeablescreen is provided between said radiation unit and the inside of theenvelope wall of said drum and concentric therewith, said screen havinga limited circumferential extension as compared with the drum andpartaking in the rotation thereof so a-s to cover a portion of said drumand substantially concentric therewith, said peripherally adjustablerelative to said drum in order to permit screening olf of a selectedportion of the original held on the outside thereof.

6. An apparatus as claimed in claim S, wherein an additional diaphragmscreen is provided between said radiation source unit and the inside ofthe envelope wall of said drum and substantially concentric therewith,and diaphragm screen being movable to screen olf said radiation sourceunift when said drum with the original record held thereon hasaccomplished a preadjustable part of a full revolution, all in order topermit the apparatus to reproduce only selected lines of the originalrecord.

References Cited UNITED STATES PATENTS Roshkind Z50-65.1 Limberger 25O-65.1 Strozynski Z50-61.1 Kalmanson Z50-61.1

RALPH G. NILSON, Primary Examiner. 10 A. L. BIRCH, Assistant Examiner.

